DropdownButtonFormField retains selected value even after setting value to null #169983
Description
Steps to reproduce
For better understanding, run the DartPad example and follow these steps:
- Use
DropdownButtonFormFieldwith items:['cat1', 'cat2', 'add category']. - Select
'add category', which triggers a function that attempts to clear the selected value (value = null).- At this point, the dropdown still displays
'add category'as the selected value.
- At this point, the dropdown still displays
- Now, select another option (e.g.,
'cat1'or'cat2') to set a new value. - Then select
'add category'again. This time, the same function clears the dropdown value correctly.
✅ If you replace DropdownButtonFormField with DropdownButton, the dropdown clears as expected in both attempts.
Expected results
The DropdownButtonFormField should immediately reflect the cleared state (i.e., no selected item) when its value is set to null, regardless of the dropdown’s previous selection.
Actual results
When value = null is triggered after selecting 'add category' directly, the dropdown continues to display 'add category' as the selected item.
Only after selecting a different value first (e.g., 'cat1'), and then selecting 'add category', does the DropdownButtonFormField correctly clear the selection and reflect the null state.
This behavior is inconsistent and does not occur when using DropdownButton, where clearing the value works immediately.
Code sample
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